1. Field of the Invention
This invention relates to an apparatus for testing sheet material such as bank notes.
2. Related Art
Such an apparatus is known from DE-PS 32 42 789. The device uses a plurality of sensors each consisting of two components. The two components are disposed on opposite sides of a transport path which transports the sheet material through the sensors. The components of the sensors on one side of the transport path are combined into a group and fastened to a separate mounting plate.
In order to permit access to the transport path in the area of the sensors, e.g. for eliminating sheet material jams or maintenance of the sensor surfaces facing the transport path, the mounting plate is pivoted and can be rotated out of the base plate plane. This rotation opens the sensor gap formed by the component of a sensor and the transport path and exposes the front side of the sensor components facing the transport path and the transport path itself. This permits elimination of a bank note jam or cleaning of the front sides of the sensor components in a simple way.
In order to prevent removal of security-relevant components of sensors by unauthorized persons, these components are protected with an alarm loop. This can be realized in the simplest case in the form of an unbridgeable electric circuit. Since the electric supply lines to the sensors need not be interrupted in the apparatus, the gap formed by the sensors can be opened without triggering an alarm.
Time-consuming adjustment of the sensors after removal of a bank note jam or maintenance of the front sides of the sensor components is unnecessary since the original adjustment is restored when the mounting plate is turned back.
A disadvantage of the apparatus is that the sensors must be disposed on an axis and parallel to each other for effective use of a mounting plate. If there is a large number of sensors this results in an elongate apparatus with a large space requirement. Further, the housings of the individual sensor components should be of like construction if possible. If the housings have different sizes the mounting plate must be adapted to the largest housing, which again involves a relatively large space requirement. In order to protect the sensor components from removal by unauthorized persons one must provide each with an alarm loop.
On these premises, the invention is based on the problem of proposing an apparatus for testing sheet material wherein the sensor gap formed by the sensor components and the transport path can be opened and which simultaneously ensures a spacesaving arrangement of the sensors and protection of the sensor components from removal by unauthorized persons.